Apparatus that (a) receives run-off water from parking lots, filling stations, etc., (b) removes any oil that is in the run-off water and (c) delivers clean water to a river have been in widespread use. Generally, such apparatus has only two stages of operation, one stage being when the run-off water entering the apparatus has a low rate of flow and the other stage being when the run-off water entering the apparatus has a high rate of flow. With such apparatus the separation of the water and the oil is inadequate.
My U.S. Pat. No. 5,746,911, granted May 5, 1998 is an improvement upon the apparatus described above. It has three stages of operation, one of which is for low rate of flow of the run-off water, a second of which is for an intermediate rate of flow of the run-off water and a third of which is for high rates of flow of the run-off water. With the apparatus described in my aforesaid patent the ineffectiveness of the prior art at intermediate flow rates was overcome.
The conventional prior art performs the entire separation process in one tank whereas my aforesaid prior patent has one tank for receiving the incoming water and for feeding the water to an outlet and another tank wherein the water is separated from the oil. The fluid in the second tank remains very calm at all times and therefore the separation process is very efficient.